window.onload=function(){
	sum.a();
}
let b=456;
let x=20;
var sum = {
	x:10,
	a(){
		this.b(function(){
			console.log(111)
			console.log(this)
		});
		setTimeout(function(){
			console.log(this.x)
		},10)
	},
	b(e){
		e&&e();
	}
}